// It is backed by only thing rfst backs any form of money: the credibility of it’s monetary properties //

Of course. That doesn't mean that all currencies are equally soundly backed, now, does it?

Bitcoin doesn’t even have any intrinsic properties. Its properties are also set by consensus genius.

// you can’t ban mathematics or code //

You can’t ban physical laws either, but somehow we manage to have speed limits. You can’t ban the laws of chemistry but somehow we manage to have laws banning drugs.

// . . . All value is subjective and relative . . . //

The word you’re looking for is “intersubjective”.